Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
The ‘gold standard’ for assessing von Willebrand Factor functional activity. Normal Ristocetin Co-Factor activity requires a normal level of full length plasma von Willebrand Multimers. The assay is especially important in determining the response of type 2 vWD patients to treatment, vW Antigen may rise in type 2 patients without a rise in function, with the potential for bleeding problems if only the antigen was used to determine response.
Specimen container paediatric:
Light blue – sodium citrate
Specimen container adult:
Light blue – sodium citrate
Minimum volume paediatric:
2.6mL
Minimum volume adult:
5.4mL
Special requirements:
Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.
Sample stability:
4 hrs
Transport requirements:
Samples should be transported to lab without delay
Freq analysis:
As required or weekly
Add on test:
[email protected] (external)
Quality assurance:
UK NEQAS Blood Coagulation
Reference ranges:
40 to 150 IU/dL
Note: For Haemostatic tests, paediatric reference ranges may be different to adult ranges.
Other info:
Used in the diagnosis of von Willebrand Disease.Performed as part of a vW Screen.